LAB EXAM #1
1. What three elements are used in an autoclave to sterilize equipment? heat, pressure, and steam
2. What is the minimum temperature an autoclave must be set at to achieve sterile condition? 125°C
3. If you are working in a lab in which an autoclave is not available, and you are pressed for time,
which would you chose to best sterilize your equipment? Hot steam or hot air? Explain why you
chose your answer. Hot steam is the best choice as you can achieve a sterile environment in a
matter of minutes whereas hot air will take several hours to achieve the same effect.
4. What type of incubator is pictured below? Fixed incubator
5. At what temperature is the fixed incubator set to, as presented in the lab video? 37°C
6. At what temperature should you refrigerate bacterial samples? Explain why this is beneficial. 4°C.
This temperature slows bacterial growth and prolongs the life of the sample.
7. What are the FOUR types of gloves presented in the lab video? Latex, Nitrile, Thermal cold,
Thermal heat
8. What THREE rules were discussed in regards to lab safety that would protect you and others from
contamination? 1. Never eat or drink in the lab
2. Always wear appropriate PPE
3. Never leave the lab wearing PPE
9. What are the main sections that should be found in a lab notebook? Name at least 4. Objective,
Procedure, Notes, Results and Deviations
LAB 2
4. How should you hold the microscope when you move it or carry it? You should hold it with one
hand on the neck and one hand under the base
5. List the four magnification strengths found on the objectives of the light microscope shown in the
lab video. 4x, 10x, 40x, 100x
, 6. As you looking through the microscope you notice your sample is slightly off-center—what
component of the microscope would be used to bring the sample into the center of the image?
Stage adjustment knobs
7. What objective power is best suited if you are uncertain what the sample is and where to begin?
4x (or lowest power objective)
8. You are viewing a sample of bacteria that is 3 mm in diameter through a 40x objective lens. The
eyepiece has a magnification power of 10x. What size will the sample appear through the eyepiece?
1200 mm in diameter (or 400x’s larger)
9. Based on the microscope shown in the lab lecture, which objectives would NOT require placing oil
on the slide? 4x, 10x and 40xResults: Magnification = objective x eyepiece
LAB 3 EXAM
1. List the 4 main steps used to prepare a WET mount and indicate which (if any) step is optional.
1 – Clean slide
2 – Circle area on slide with wax/hydrophobic pen
3 – Apply organism to slide
4 – View under microscope
*Note: there are no optional steps in the wet mount.
2. When preparing a glass slide for a dry mount, what cleaning solution was used? 70% ethanol
3. You wish to study the motility of a particular bacterium. What type of mounting technique would
you use? Explain your answer. A wet mount technique is the best technique to use when
studying motility of an organism because the sample remains viable (heat fixing kills the
sample).
4. What dye do Gram-negative bacteria primarily retain? Safranin
5. Why are Gram-positive bacteria able to retain the crystal violet dye? They contain a thick
peptidoglycan layer in their cell wall that readily retains the dye.
6. Identify the Gram status (positive or negative) and shape of the bacteria pictured below. Gram-
Negative; Bacillus (rod)
1. What three elements are used in an autoclave to sterilize equipment? heat, pressure, and steam
2. What is the minimum temperature an autoclave must be set at to achieve sterile condition? 125°C
3. If you are working in a lab in which an autoclave is not available, and you are pressed for time,
which would you chose to best sterilize your equipment? Hot steam or hot air? Explain why you
chose your answer. Hot steam is the best choice as you can achieve a sterile environment in a
matter of minutes whereas hot air will take several hours to achieve the same effect.
4. What type of incubator is pictured below? Fixed incubator
5. At what temperature is the fixed incubator set to, as presented in the lab video? 37°C
6. At what temperature should you refrigerate bacterial samples? Explain why this is beneficial. 4°C.
This temperature slows bacterial growth and prolongs the life of the sample.
7. What are the FOUR types of gloves presented in the lab video? Latex, Nitrile, Thermal cold,
Thermal heat
8. What THREE rules were discussed in regards to lab safety that would protect you and others from
contamination? 1. Never eat or drink in the lab
2. Always wear appropriate PPE
3. Never leave the lab wearing PPE
9. What are the main sections that should be found in a lab notebook? Name at least 4. Objective,
Procedure, Notes, Results and Deviations
LAB 2
4. How should you hold the microscope when you move it or carry it? You should hold it with one
hand on the neck and one hand under the base
5. List the four magnification strengths found on the objectives of the light microscope shown in the
lab video. 4x, 10x, 40x, 100x
, 6. As you looking through the microscope you notice your sample is slightly off-center—what
component of the microscope would be used to bring the sample into the center of the image?
Stage adjustment knobs
7. What objective power is best suited if you are uncertain what the sample is and where to begin?
4x (or lowest power objective)
8. You are viewing a sample of bacteria that is 3 mm in diameter through a 40x objective lens. The
eyepiece has a magnification power of 10x. What size will the sample appear through the eyepiece?
1200 mm in diameter (or 400x’s larger)
9. Based on the microscope shown in the lab lecture, which objectives would NOT require placing oil
on the slide? 4x, 10x and 40xResults: Magnification = objective x eyepiece
LAB 3 EXAM
1. List the 4 main steps used to prepare a WET mount and indicate which (if any) step is optional.
1 – Clean slide
2 – Circle area on slide with wax/hydrophobic pen
3 – Apply organism to slide
4 – View under microscope
*Note: there are no optional steps in the wet mount.
2. When preparing a glass slide for a dry mount, what cleaning solution was used? 70% ethanol
3. You wish to study the motility of a particular bacterium. What type of mounting technique would
you use? Explain your answer. A wet mount technique is the best technique to use when
studying motility of an organism because the sample remains viable (heat fixing kills the
sample).
4. What dye do Gram-negative bacteria primarily retain? Safranin
5. Why are Gram-positive bacteria able to retain the crystal violet dye? They contain a thick
peptidoglycan layer in their cell wall that readily retains the dye.
6. Identify the Gram status (positive or negative) and shape of the bacteria pictured below. Gram-
Negative; Bacillus (rod)
